Caira Frank C, Stock Stuart R, Gleason Thomas G, McGee Edwin C, Huang Jie, Bonow Robert O, Spelsberg Thomas C, McCarthy Patrick M, Rahimtoola Shahbudin H, Rajamannan Nalini M
Division of Cardiology and Cardiothoracic Surgery, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA.
J Am Coll Cardiol. 2006 Apr 18;47(8):1707-12. doi: 10.1016/j.jacc.2006.02.040. Epub 2006 Mar 20.
The goal of this research was to define the cellular mechanisms involved in myxomatous mitral valve disease and calcific aortic valve disease and to redefine the term degenerative valve disease in terms of an active cellular biology.
"Degenerative" valvular heart disease is the primary cause of regurgitant and stenotic valvular lesion in the U.S. However, the signaling pathways are not known. We hypothesize that valve degeneration occurs due to an osteoblastic differentiation process mediated by the low-density lipoprotein receptor-related protein 5 (Lrp5) signaling pathway to cause valve thickening.
We examined human diseased valves: myxomatous mitral valves (n = 23), calcified tricuspid aortic valves (n = 27), calcified bicuspid aortic valves (n = 23), and control tissue from mitral and aortic valves (n = 40). The valves were examined by reverse transcriptase-polymerase chain reaction, Western blot, and immunohistochemistry for signaling markers important in osteoblast differentiation: Sox9 and Cbfa1 (transcription factors for osteoblast differentiation); Lrp5 and Wnt3 (osteoblast differentiation signaling marker), osteopontin and osteocalcin (osteoblast endochrondral bone matrix proteins), and proliferating cell nuclear antigen (a marker of cell proliferation). Cartilage development and bone formation was measured by Alcian blue stain and Alizarin red stain. Computed Scano MicroCT-40 (Bassersdorf, Switzerland) analysis measured calcium burden.
Low-density lipoprotein receptor-related protein 5, osteocalcin, and other osteochrondrogenic differentiation markers were increased in the calcified aortic valves by protein and gene expression (p > 0.001). Sox9, Lrp5 receptor, and osteocalcin were increased in myxomatous mitral valves by protein and gene expression (p > 0.001). MicroCT was positive in the calcified aortic valves and negative in the myxomatous mitral valves.
The mechanism of valvular heart disease involves an endochondral bone process that is expressed as cartilage in the mitral valves and bone in the aortic valves. Up-regulation of the Lrp5 pathway may play a role in the mechanism for valvular heart disease.
本研究的目标是明确黏液瘤样二尖瓣疾病和钙化性主动脉瓣疾病所涉及的细胞机制，并从活跃的细胞生物学角度重新定义退行性瓣膜病这一术语。
“退行性”心脏瓣膜病是美国反流性和狭窄性瓣膜病变的主要原因。然而，其信号通路尚不清楚。我们假设瓣膜退变是由于由低密度脂蛋白受体相关蛋白5（Lrp5）信号通路介导的成骨细胞分化过程导致瓣膜增厚。
我们检查了人类病变瓣膜：黏液瘤样二尖瓣（n = 23）、钙化三尖瓣主动脉瓣（n = 27）、钙化二叶式主动脉瓣（n = 23），以及二尖瓣和主动脉瓣的对照组织（n = 40）。通过逆转录聚合酶链反应、蛋白质印迹法和免疫组织化学检查瓣膜中对成骨细胞分化重要的信号标志物：Sox9和Cbfa1（成骨细胞分化的转录因子）；Lrp5和Wnt3（成骨细胞分化信号标志物）、骨桥蛋白和骨钙素（成骨细胞软骨内骨基质蛋白），以及增殖细胞核抗原（细胞增殖标志物）。通过阿尔新蓝染色和茜素红染色测量软骨发育和骨形成。采用瑞士巴塞尔多夫的Computed Scano MicroCT - 40分析测量钙负荷。
通过蛋白质和基因表达，钙化主动脉瓣中的低密度脂蛋白受体相关蛋白5、骨钙素和其他骨软骨生成分化标志物增加（p > 0.001）。通过蛋白质和基因表达，黏液瘤样二尖瓣中的Sox9、Lrp5受体和骨钙素增加（p > 0.001）。MicroCT在钙化主动脉瓣中呈阳性，在黏液瘤样二尖瓣中呈阴性。
心脏瓣膜病的机制涉及软骨内骨过程，在二尖瓣中表现为软骨，在主动脉瓣中表现为骨。Lrp5通路的上调可能在心脏瓣膜病机制中起作用。
